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Title: Model systems for exploring new therapeutic interventions and disease mechanisms in spinal muscular atrophies (SMAs)
Author: Sleigh, James Nicholas
ISNI:       0000 0004 2745 8265
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2012
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Spinal muscular atrophy (SMA) and Charcot-Marie-Tooth disease type 2D (CMT2D)/distal SMA type V (dSMAV) are two incurable neuromuscular disorders that predominantly manifest during childhood and adolescence. Both conditions are caused by mutations in widely and constitutively expressed genes that encode proteins with essential housekeeping functions, yet display specific lower motor neuron pathology. SMA results from recessive inactivating mutations in the survival motor neuron 1 (SMN1) gene, while CMT2D/dSMAV manifests due to dominant point mutations in the glycyl-tRNA synthetase (GlyRS) gene, GARS. Using a number of different model systems, ranging from Caenorhabditis elegans to the mouse, this thesis aimed to identify potential novel therapeutic compounds for SMA, and to increase our understanding of the mechanisms underlying both diseases. I characterised a novel C. elegans allele, which possesses a point mutation in the worm SMN1 orthologue, smn-1, and showed its potential for large-scale screening by highlighting 4-aminopyridine in a screen for compounds able to improve the mutant motility defect. Previously, the gene encoding three isoforms of chondrolectin (Chodl) was shown to be alternatively spliced in the spinal cord of SMA mice before disease onset. I performed functional analyses of the three isoforms in neuronal cells with experimentally reduced Smn levels, and determined that the dysregulation of Chodl likely reflects a combination of compensatory mechanism and contributor to pathology, rather than mis-splicing. Finally, working with two Gars mutant mice and a new Drosophila model, I have implicated semaphorin-plexin pathways and axonal guidance in the GlyRS toxic gain-of-function disease mechanism of CMT2D/dSMAV.
Supervisor: Talbot, Kevin; Davies, Kay Sponsor: Medical Research Council
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Motor neurone degenerative disease ; Neuroscience ; Muscle & Nerve (Neuroscience) ; Neurogenetics ; Genetics (medical sciences) ; Biology (medical sciences) ; spinal muscular atrophy (SMA) ; survival motor neuron (SMN) ; Charcot-Marie-Tooth (CMT) disease ; motor neuron ; neuromuscular disease ; neuropathy ; neuromuscular junction (NMJ) ; model organisms ; drug screening ; Caenorhabditis elegans ; Drosophila melanogaster